Through　high-precision　engraving,self-affine　sandstone　joint　surfaces　with　various　joint　roughness　coefficients(JRC=3.21-12.16)were　replicated　and　the　shear　sliding　tests　under　unloading　normal　stress　were　conducted　regarding　various　initial　normal　stresses(1-7　MPa)and　numbers　of　shearing　cycles(1-5).The　peak　shear　stress　of　fractures　decreased　with　shear　cycles　due　to　progressively　smooth　surface　morphologies,while　increased　with　both　JRC　and　initial　normal　stress　and　could　be　verified　using　the　nonlinear　Barton-Bandis　failure　criterion.The　joint　friction　angle　of　fractures　exponentially　increased　by　62.22％-64.87％with　JRC　while　decreased　by　22.1％-24.85％with　shearing　cycles.After　unloading　normal　stress,the　sliding　initiation　time　of　fractures　increased　with　both　JRC　and　initial　normal　stress　due　to　more　tortuous　fracture　morphologies　and　enhanced　shearing　resistance　capacity.The　surface　resistance　index(SRI)of　fractures　decreased　by　4.35％-32.02％with　increasing　shearing　cycles　due　to　a　more　sig-nificant　reduction　of　sliding　initiation　shear　stress　than　that　for　sliding　initiation　normal　stress,but　increased　by　a　factor　of　0.41-1.64　with　JRC.After　sliding　initiation,the　shear　displacement　of　fractures　showed　an　increase　in　power　function.By　defining　a　sliding　rate　threshold　of　5　×　10-5　m/s,transition　from＂quasi-static＂to＂dynamic＂sliding　of　fractures　was　identified,and　the　increase　of　sliding　acceler-ation　steepened　with　JRC　while　slowed　down　with　shearing　cycles.The　normal　displacement　experi-enced　a　slight　increase　before　shear　sliding　due　to　deformation　recovery　as　the　unloading　stress　was　unloaded,and　then　enhanced　shear　dilation　after　sliding　initiation　due　to　climbing　effects　of　surface　asperities.Dilation　was　positively　related　to　the　shear　sliding　velocity　of　fractures.Wear　characteristics　of　the　fracture　surfaces　after　shearing　failure　were　evaluated　using　binary　calculation,indicating　an　increasing　shear　area　ratio　by　45.24％-91.02％with　normal　stress.